Car is a 92 RS with the 305 tbi. It has the single fan setup. The fan does not turn on when checking for codes. The fan does work while the AC is engaged. What could the problem be?

 

Fan switch on passenger side of head. Lots of threads on this topic with a wide variety of solutions can be found by doing a search on "fan switch" Or the connector could be faulty. Ground the wire going to the switch with the key on. If the fan works, that's the problem.

 

I thought it could be the fan switch but wasn't sure if that still controlled the fan while in diagnostic mode. Will check out your suggestions.

 

Yeah, on the single fan system you have, the only things that control the fan are the switch and the relay. Computer has nothing to do with it

 

Fan not supposed to come on when checking codes. Only time fan comes on is when A/C is on, or when coolant temp gets to up to the fan switch temp.

 

fans not on during codes and mabey you have an a/c pressure switch problem